Finding the Fourth Proportional to 1,139.45, 1,573.30 and 1,121.29

Step by Step Solution

1. Step 1: Write the proportion equation
   1,139.45 : 1,573.30 = 1,121.29 : x
2. Step 2: Convert to fraction form
   1,139.45/1,573.30 = 1,121.29/x
3. Step 3: Cross multiply
   1,139.45x = 1,573.30 × 1,121.29
4. Step 4: Simplify right side
   1,139.45x = 1,764,118.82
5. Step 5: Solve for x
   x = 1,764,118.82/1,139.45
6. Step 6: Final answer
   x = 1,548.23